what tense will use after no sooner had.what will be te tense of other part of the sentence?what about scarcely had?
No sooner ~ than is a two-part adverb that should be tied up together as a set grammatically. However,
than is quite commonly replaced by
when,
then or even omitted at all. (I'm not judging but that's the way it is.)
Coming back to your question, either past or past perfect is OK with
no sooner (I prefer past perfect though), but with
scarcely/hardly/barely only past perfect is acceptable to my knowledge.
No sooner had he arrived than he left.
No sooner did he arrive than he left.
Scarcely had he arrived when he left.
Hope it helped.